I have experience with 2 adoptions; 1 resulted in me becoming the Mom of a beautiful daughter, 1 was terminated by my DH & me. In the terminated process, we were matched with a little boy that had been in foster care (with his sister) since he was a year old, until we took him in at age 8. His birth mother left these 2 babies (the sister was 2) with her own mom, and didn't return. Grandma got tired of caring for 2 little ones & had the police take them into custody, which resulted in the foster system. The woman they were placed with was a friend of Grandma's, so you'd think everything would have been ok. Over the years, those 2 kids, along with 4 others, were abused in every sense of the word by the foster "mom's" 40-something y/o son. ( the younger ones were even chained by a dog-collar to bed frames at night; Chicago's WGN-TV did a huge expose on this case). Those 2 kids were in foster care for 7 years because the system wanted to give their birth mother every chance. The birth father's rights weren't terminated during that time, either. Those kids suffered because their "mother" had rights--but they didn't.
I have a really hard time with birthparents changing their minds, and with their rights taking precedence over the right of the child. IMO, there should be a set time frame when the whole deal can be undone. Too often, you see heart-wrenching stories about 3 year old children being ripped from their parents' arms because their birthparent changed their mind.